docs: def save(self, file):
          """ Saves the :class:`~pypot.primitive.move.Move` to a json file.
  
          .. note:: The format used to store the :class:`~pypot.primitive.move.Move` is extremely verbose and should be obviously optimized for long moves.
          """
          d = {
              'framerate': self.framerate,
              'positions': self._timed_positions,
          }
          json.dump(d, file, indent=2)